The present invention relates to a process for preparing a carbon material oxidation resistance.
A carbon/carbon composite is a material capable of retaining high strength and high elastic modules even at high tempertures higher than 1,000.degree. C. in an inert atmosphere, and having a small thermal expansion coefficient. Its application to components of aeronautic and sapce machinery and devices, brake material and furnace material is expected. In air, however, it is oxidized and wasted at a temperature of about 500.degree. C. or higher.
There has been made an attempt of coating the surface of a carbon/carbon composite with a ceramic material to improve the oxidation resistance of the composite. But since the thermal expansion of the carbon/carbon composite as base material and that of the ceramic material are different from each other, there occurs delamination at the interface or cracking of the coating, so the function of the composite is not exhibited to a satisfactory extent.
Having made studies about a process for improving the oxidation resistance of a carbon/carbon composite, the present inventors found out and already proposed a process for preparing a carbon/carbon composite having oxidation resistance. According to this previously- o proposed process, there is used a carbon/carbon composite comprising 10-70 vol % of carbon fibers and 5-90 vol % of a carbonaceous matrix and having an open voids content of 10-55%, and carbon and/or a ceramic material are(is) deposited and filled into the open voids of the carbon/carbon composite by vapor phase decomposition, then the surface of this deposit is coated with a ceramic material or both a ceramic material and carbon by vapor phase decomposition.
It is the object of the present invention to provide a carbon/carbon composite having superior oxidation resistance.